The process of building custom applications and tools that interact with Microsoft SharePoint, including SharePoint Online in Microsoft 365.
Thank you for sharing your concerns.
As your description, this issue might be related to the search indexing behavior of an older (legacy) SharePoint site. You may first review the AI's suggestion and follow these steps to troubleshoot it:
Verify advanced permissions
Go to the affected site > Settings
Select Site permissions > Advanced permission settings.
Confirm whether the site is using unique permissions.
Ensure your account has at least Read permission on the site.
Check search visibility settings
Go to Settings > Site information > select View all site settings.
Under Search, click Search and offline availability.
Confirm that the following setting is enabled:
Allow this site to appear in search results should set to Yes.
If this option is set to No, the site may not appear as a selectable source in the Events or Highlighted Content web parts, even after reindexing.
Additionally, you could try to use the SharePoint search bar and try searching for: “Technical Services” or contentclass:STS_Site.
Please let me know whether the site appears in the search results.
After you complete these checks, kindly share the results with us to better address the issue.
Please understand that our initial reply may not always immediately resolve the issue. However, with your help and more detailed information, we can work together to find a solution.
Note: Please follow the steps in [our documentation] to enable e-mail notifications if you want to receive the related email notification for this thread.